Technical Field
The present disclosure relates to positioning systems (such as, navigation systems) comprising inertial sensors, such as an example, mixed GNSS and Dead Reckoning navigation systems.
Description of the Related Art
Global navigation satellite systems, GNSSs, include constellations of earth orbiting satellites that constantly transmit orbit data and ranging signals to receivers. An example of a GNSS is the Global Positioning Systems (GPS). A GPS receiver receives the satellite signal information from at least four satellites and calculates the receiver position by measuring the range of the receiver from each used satellite and determining the accurate position of each used satellite in a suitable reference coordinate system.
However, there are many environmental situations that cause an attenuation of the received satellites signal. Low signal strength conditions can occur in challenging environments such as urban canyons, under foliage, inside tunnels etc.
GNSS systems can be aided by inertial sensors in order to provide the receiver position even in conditions where satellite signals are not available. Particularly, so called Dead Reckoning (DR) techniques are known to determine vehicle position by employing inertial sensors, such as accelerometers and gyroscopes, and odometers.
The recent introduction of gyroscopes manufactured in MEMS (Micro Electro Mechanical Systems) technology has decreased the sensor costs.
However, in high-accuracy applications such like DR, raw signal outputted by MEMs sensors cannot be used directly, because it embeds intrinsic error factors that need to be compensated. The compensation process is commonly known as calibration in which a sensor can be modelled using one or more calibration parameters, whose behavior across device lifetime can be influenced by different factors (e.g., aging, environmental conditions).